#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include <poll.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>

//char *bat_power_path = "/sys/class/power_supply/BAT1/energy_now";
//char *bat_capacity_path =  "/sys/class/power_supply/BAT1/capacity";

const char *bat_base_path = "/sys/class/power_supply/";

void usage (void)
{
	printf("usage: bmon [-w]\n");
}

int main (int argc, char *argv[])
{
	int wflag = 0;
	int opc;
	while ((opc = getopt(argc, argv, "w")) != -1) {
		switch (opc) {
		case 'w':
			wflag = 1;
			break;
		default: /* '?' */
			usage();
			exit(1);
		break; 
		}
		
	}

	DIR *bdir = NULL;
	if (!(bdir = opendir(bat_base_path)))
		perror("error opening base directory");
	
	struct dirent *ent = NULL;
	int *fd_list = NULL;
	int fd_num = 0;
	for (;;) {
		errno = 0;
		if (!(ent = readdir(bdir))) {
			if (errno)
				perror("error reading base directory");
			else break;
		}
		
		if (!strstr(ent->d_name, "BAT1"))
			continue;

		int fd;
		char path[sizeof(bat_base_path) + 256 + 64];
		strcpy(path, bat_base_path);
		strcat(path, ent->d_name);
		if (wflag)
			strcat(path, "/energy_now");
		else strcat(path, "/capacity");

		if ((fd = open(path, O_RDONLY | O_NONBLOCK)) != -1) {
			int *tmp = NULL;
			tmp = realloc(fd_list, sizeof(int) * (fd_num + 1));
			if (!tmp)
				perror("failed realloc");
			fd_list = tmp;
			fd_list[fd_num] = fd;
			fd_num++;
		} else printf("err: %s\n", strerror(errno));
				
	}
	closedir(bdir);
	if (!fd_num)
		printf("no files were opened\n");
	
	for (int i = 0; i < fd_num; i++)
		close(fd_list[i]);
	return 0;
}